This invention relates generally to semiconductor integrated device fabrication, and more particularly the invention relates to process enhancement through use of molybdenum interface layers for moly plugs.
The use of refractory metals in high temperature interconnect structures is known, see for example U.S. Pat. Nos. 4,152,823, 4,265,935, and 4,042,953 all for high temperature refractory metal contact assembly and multiple layer interconnect structures. In these patents a sandwich structure having outer layers of silicon and a core material of a refractory material such as molybdenum are used as interconnect lines.
In thin film resistor technology, processing difficulties are encountered due to high temperature processing of aluminum contacts on the resistors. Typically, the thin film resistors comprise a sputtered mixture of silicon, chromium, carbon, and boron. While the thin film resistors have highly precise values, temperature cycling can cause non-uniformity in contact resistances. This is particularly a problem where laser trimming is used to establish desired resistance values and in hermetically sealing the circuits and packages.
The present invention is directed to enhanced processing of semiconductor integrated circuit in which thin film resistors and the semiconductor diffusions are interconnected with a metal such as aluminum which is susceptible to high temperature processing.